In an assembled battery configured of a plurality of series connected power storage cells, there is a need to suppress the variances of the voltages (electromotive force) of the power storage cells in order to prevent a discharge capacity reduction and life shortening. Particularly, as in a power storage device used for electric vehicles and the like, there is a need to precisely suppress the voltage variances of the power storage cells in an assembled battery configured of multiple power storage cells.
As a mechanism for equalizing the voltages of the power storage cells, for example, PTL 1 discloses a so-called converter type balance correction method where one end of the inductor L is connected beforehand to a connection point of the series connected secondary batteries B1, B2 and the voltages of the batteries B1 and B2 are equalized by performing for an appropriate period, a repeated short time alternating operation (switching operation) between the first mode where an electric current flows through the first closed circuit formed by connecting the other end of the inductor L to the other end of the battery B1 and the second mode where an electric current flows through the second closed circuit formed by connecting the other end of the inductor L to the other end of the battery B2.